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hku-mars / FAST-LIVO

A Fast and Tightly-coupled Sparse-Direct LiDAR-Inertial-Visual Odometry (LIVO).
GNU General Public License v2.0
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Hardware time sync #21

Closed Tomato1107 closed 1 year ago

Tomato1107 commented 2 years ago

Are there any suggestions for aligning camera and lidar timestamps？I tried two hardware sync signals, 1hz (PPS sync) for lidar and 10hz for camera. It was found that there was a time difference.

Tomato1107 commented 2 years ago

nxplayer bin_4M6d2PncJ8

satyajitghana commented 2 years ago

same here

Camilochiang commented 1 year ago

@Tomato1107, If im not wrong what is happening, if you have a correct hardware sync, is that you are synchronizing the start of the measurement and not when you are reciving the ROS message. That means that the camera take significantly longer to capture the image compared with the lidar and IMU. Of course this depend of the camera that you are using, ROS package and the computer speed. Why do you want to have the messages arriving at the same time?

Tomato1107 commented 1 year ago

I'm very confused about timestamps. Every time I run the fastlivo, it seems to be different.

avia

Camilochiang commented 1 year ago

You don’t need to run any algorithm to check time stamps . 

roscore #in one tab of terminal
rqt_graph YOURBAG.bag

please run it with your bags and you will get always the same time stamps . Is your image bellow always the same bag?

Tomato1107 commented 1 year ago

I recorded several rosbags, the time difference also seemed to be different when I run fastlivo. It really takes some time for the camera to deal with the image, currently I just use the 10Hz signal to trigger it. You can also compare different rosbags to check the results.

Camilo Chiang @.***>于2022年12月2日 周五4:20写道：

You don’t need to run any algorithm to check time stamps .

roscore #in one tab of terminal

rqt_graph YOURBAG.bag

please run it with your bags and you will get always the same time stamps . Is your image bellow always the same bag?

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xuankuzcr commented 11 months ago

The synchronization scheme has been updated, as mentioned in Issue #44 @Tomato1107 @Camilochiang